Apparatus for closing drums

ABSTRACT

A method and apparatus for closing the ends of plastic bung or stopper drums. The apparatus comprises an end closing coupling for a bung drum composed of plastic material wherein the upper edge of the body of the drum has a circumferential bordure including an inwardly projecting groove and an inwardly bent edge. An end closure for the bung drum is fashioned with a circumferential marginal bead having grooves operable to receive the inwardly projecting groove and inwardly bent edge of the drum body. The method comprises engagement of the inwardly projecting groove and bent edge with corresponding portions of the end closure marginal bead when the inwardly projecting groove and bent edge are in a warm state and subsequently cooling the projecting groove and bent edge to provide a secure shrink fit closure coupling.

United States Patent [1 1 Hammes 1 Oct. 14, 1975 1 APPARATUS FOR CLOSINGDRUMS [76] Inventor: Wilhelm Hammes, Hauptstrasse 38,

[30] Foreign Application Priority Data May 30, 1972 Germany 2226217 [52]US. Cl. 220/67; 220/76; 220/307; 220/308 [51] Int. C1. B65D 39/00; B65D7/42 [58] Field of Search 220/24 A, 24 B, 24.5, 60, 220/76.67, 75, 66,306, 307, 308; 215/41, 47

[56] References Cited UNITED STATES PATENTS 2,674,472 4/1954 Meyer215/47 2,872,060 2/1959 Brune et al.. 215/47 3,531,013 9/1970 Hammes220/55 AN 3,542,913 12/1967 Robinson et a1. 220/60 R 3,771,681 11/1973Mart 215/41 3,780,897 12/1973 Wassiliefi 1 215/41 3,792,797 2/1974Mrusek et a1. 220/60 R FOREIGN PATENTS OR APPLICATIONS 557,424 2/1957Italy 215/364 524,500 12/1953 Belgium 215/364 769,054 2/1957 UnitedKingdom 215/364 77,929 4/1955 Netherlands 215/364 PrimaryExaminer-William 1. Price Assistant Examiner.loseph M. Moy

Attorney, Agent, or Firm-Burns, Doane, Swecker &

Mathis 57 ABSTRACT A method and apparatus for closing the ends ofplastic bung or stopper drums.

The apparatus comprises an end closing coupling for a bung drum composedof plastic material wherein the upper edge of the body of the drum has acircumferential bordure including an inwardly projecting groove and aninwardly bent edge. An end closure for the bung drum is fashioned with acircumferential marginal bead having grooves operable to receive theinwardly projecting groove and inwardly bent edge of the drum body.

The method comprises engagement of the inwardly projecting groove andbent edge with corresponding portions of the end closure marginal beadwhen the inwardly projecting groove and bent edge are in a warm stateand subsequently cooling the projecting groove and bent edge to providea secure shrink fit closure coupling.

7 Claims, 1 Drawing Figure U.S. Patent Oct. 14,1975

APPARATUS FOR CLOSING DRUMS BACKGROUND OF THE INVENTION The inventionrelates to a bung drum which comprises a drum body made ofthermoplastics by a blowmolding process and an end closure produced byway of an injection molding process.

Bung drums made of plastics which have become known hitherto aretypically made in one piece by a blow-molding method, whereby one or twobungs or stoppers are configured in the mold parting line. Thesestoppers mostly are located in corresponding recesses of an end closureso as to provide a flat stacking surface. For reasons of stressdistribution under a stacking load such drums, in most cases, are madewith a slight bulge and at the transition to the lower and upper endclosures they are given relatively large radii. Such drums with theircontours rounded and smooth on all sides are very difficult tomanipulate as compared to steel, metal drums which are provided withdrawn-in bottoms and a folded edge, as is prevalent in the case of largevolumes. The customary blown-in gripping troughs at the upper end of thejacket offer only an insufficient possibility for manipulating and theyweaken the statics of the drum in an unjustifiable manner.

One solution which has been at least theorized is to provide a tipstretched crane ring on the upper closure. Such a device, however, isnot suitable for widespread manipulation by hand. Moreover, the upperclosure of such a drum broken up by the crane ring does not have therequired strength in the case of a strain when fallmg.

The bungs or stoppers which were formed during blowing by molding of thehot material cannot be produced with the necessary precision because ofthe shrinking process and tensions which develop during cooling off.Mostly crooked or oval bungs develop which require special embodimentsof bungs in order to bridge the clearance which then, however, will notpermit the use of a large number of existing devices for filling,closing, sealing and emptying of drums. The upper end closure, which maybe uneven because of the same reasons and is moreover increasinglyexposed to abrasion, does not permit the often used marking with thedesignation of the filling material and with instructions for use.Likewise, the frequently used loading by means of vacuum lift isimpossible because of the uneven upper end closure.

Another very serious disadvantage of such drums results from the processof production during which a parison of plastic material is squeezed offat both ends, is welded and is then blown against the inside wall of themold. As a result of the squeezing out at the two ends this preform isno longer rotationally symmetric at the decisive points as a result ofwhich differences in the thickness of the wall result during blowingbecause of the succeeding uneven stretching of the material, whichdifferences can range within the order magnitude of 1:3. Particularly onthe upper end closure, where for purposes of forming the bungs lyingclose to the edge, the parison must additionally be expanded, thesedifferences in the thickness of the wall occur in an extreme form. Inorder to fulfill, in the case of drums produced in this way, therequirement for a minimum of the thickness of the wall, adisproportionally high consumption of material is required which, besideconsiderable additional costs, also reduces the efficiency of theproduction. Thus it has also turned out that drums with lids with anapproximate full opening where the preform is squeezed off only at thelower end closure have a considerably better distribution of thethickness of the wall and can be produced considerably more quickly.

MAJOR OBJECTS AND BRIEF SUMMARY OF THE INVENTION Therefore, theinvention is based on the objective of developing a bung drum which hason the one hand an almost even thickness of the wall corresponding tothe standards known for open head drums and on the other hand permitseasy and safe handling as a result of an encircling reinforced bead atthe edge of a recessed upper bottom. Beyond that the requirements, suchas the use of standard bungs, the possibility to take markings on theupper bottom and the use of vacuum lift during loading should also befulfilled at the same time.

According to the invention, these and other objectives are achieved by abung drum made of plastics with one or more bung openings. This bungdrum at its upper edge of the body of the drum blow-molded out ofthermo-plastic material has a groove-like bordure with an inwardly drawngroove and a likewise inwardly bent edge which engages with thecorresponding grooves by way of the anticlinal bulge of the grooveprojecting inwardly and the inwardly directed upper edge, which groovesare disposed in the outside surface of an edge bead circling the upperend closure and which forms with said bead a perpendicular undissolvableconnection.

The body of the bung drum according to the invention is to consist ofthermoplastics, as for example the high molecular high densitypolyethylene, and advantageously it is produced according to thepreviously mentioned blow-molding process, whereby the preform issqueezed off only at the lower end closure while at the upper edge ofthe body of the drum the approximate full opening is maintained.

According to the invention the upper edge of the body of the drum issupposed to have a groove-like bordure with an inwardly drawn-in grooveand an inwardly bent edge. Advantageously the groove-like bordureconstitutes one piece with the body of the drum and is molded togetherwith the latter.

Basically the bordure can have any given shape as long as it has aninwardly drawn groove and an inwardly bent edge. A groove-like bordurewhich is developed S-shaped has proven itself particularly well. Forthis purpose the upper edge of the body of the drum is first drawn-ingroove-like to a bead projecting inwardly and, after a groove-likeannular recess arched outwardly to a bead, it is again bent inwardlyperpendicularly to the axis of the body of the drum. The groove drawninwardly together with the bead arched outwardly and disposed above itand the drawn-in upper bottom form a sure possibility for gripping forthe purpose of handling the bung drum according to the invention byhand. The safety of the grip can be improved still further by outsideperpendicular corrugation of the bead arched outwardly and of the insidesurface of the edge of the upper bottom.

With the bead-like arching projecting inwardly and the inwardly directedupper edge, the bordure engages with the grooves which are disposed inthe outside surface of an edge bead circling the upper bottom. For thispurpose the upper bottom is advantageously developed as a drawn-inbottom which is provided with a marginal bead which standsperpendicularly in relation to the upper surface of the upper bottom andwhich constitutes one piece with the latter. At the perpendicularoutside of this marginal bead two encircling grooves have been disposed.The lateral parts limiting these grooves project from the marginal beadsof the upper bottom and encircle the latter annularly. The said elementsdisposed in the middle part of this marginal bead can be connected withperpendicular bridges in order to counteract the distortion of themarginal bead of the upper end closure.

Advantageously the upper end closure is produced by way of an injectionmolding method, whereby the bungs are configured in the entry of theupper end closure for a better sealing of the connection between thebordure and the marginal bead. At the upper end closure a gasket can beinserted in at least one of the grooves circling the marginal bead ofthe upper end closure preferably into the upper one, which gasket ispressed by the engaging part of the bordure firmly against the innersurface of the pertinent groove. The gasket preferably has a round crosssection and can consist of traditional, especially elastic material.Gaskets made of foam rubber and of foamed polyurethane have proventhemselves particularly well.

For the production of the bung drum the parts of the bordure at theupper edge of the body of the drum projecting inwardly, are made toengage in a warm state with the grooves of the marginal bead disposed onthe upper bottom and are then cooled.

THE DRAWINGS The design of the engaging elements of the head of the drumand the upper bottom can take place naturally in many different ways. Inthis respect, the drawing merely shows one embodiment of the bung drumaccording to the invention by way of example.

DETAILED DESCRIPTION The body 1 of the drum 'forms one piece with the S-shaped bordure 2. The bordure 2 has a bead-like bulge or arching 3projecting inwardly and a generally radially inwardly directed edge orlip 4 which is separate from the bead-like arching 3 by an outwardlyarched groove 5. The groove 5 is formed by an intermediate portion ofthe bordure and extends generally radially outwardly. The bead-likearching 3 forms on the outside an inwardly drawn groove 18 extending ina generally radial direction, which serves as an encircling grippingrecess. In addition, the outside of the bordure 2 is provided with acorrugation 17. The drawn-in upper bottom 6 is provided on the outsidesurface with the marginal bead 7 with the grooves 8 and 9, which arelimited by and thus defined by axially spaced lateral flange parts 10and 11 or 12 and 13. These flange parts extend generally radiallyoutwardly to define the generally radially inwardly projecting grooves 8and 9. A gasket 14 is inserted into the groove 9. The lateral parts 11and 12 are connected by bridges 15 at intervals. In the entry of theupper bottom 6, bungs 16 have been provided. The inside surface of themarginal bead 7 is likewise provided with a corrugation 17.

In order to establish the connection between the body 1 of the drum andthe upper bottom 6, the latter is inserted into the warm bordure 2 insuch a way that the inwardly projecting arching 3 and the inwardly bentedge 4 ofthe bordure 2 are caught easily by the grooves 8 and 9 of themarginal bead 7 located on the upper bottom 6. The outside diameter ofthe lateral part 11 and of the bridges 15 is kept smaller than theoutside diameter of the lateral part 12, as a result of which a safeguidance results during insertion and subsequent engagement of the upperbottom 6 with the bordure 2. As a result ofa subsequent cooling of thebordure 2 the latter shrinks to such a point that the projecting arching3 is firmly pressed into the groove 8 and the inwardly bent edge 4 intothe groove 9. In this fashion, and as can be viewed in the figure, theflange parts 10 and 11 extend radially outwardly beyond the radial innerextent of the bulge 3 such that these flange parts 10, 11 firmly engageopposite, longitudinally spaced surfaces 20 and 21, respectively, of thebulge 3. Likewise, the flange parts 12 and 13 extend radially outwardlybeyond the radial inner extent of the lip 4 such that these flange partsl2, l3 firmly engage opposite, longitudinally spaced surfaces 23 and 24,respectively, of the lip 4. The flange parts 11 and 12 are, in thisembodiment, both received within the groove 5. The trimmed and thuscompletely smooth front surface of the edge 4 at the same timecompresses the gasket 14 so that a safe seal of the connection isguaranteed. The outwardly arched groove 5 of the bordure 2 of the drumis filled by the two lateral parts 11 and 12 of the grooves 8 and 9which are connected for the purpose of reinforcement with a number ofbridges 15 disposed at a distance from one another. The L-shaped lateralpart 10 of the groove 8 engages below the bead-like arching 3 of thebordure 2 projecting inwardly and causes a double anchoring of the upperbottom 6 in the bordure 2 of the body 1 of the drum. The corrugation 17on the bordure and on the inside surface of the marginal bead 7increases the non-slipping quality and thus the possibility for handlingof the drum according to the invention which is still further improvedby the encircling gripping recess 18.

SUMMARY OF MAJOR ADVANTAGES OF THE INVENTION The grooves and projectionsof the bordure of the drum and the upper end closure being engaged withone another, together constitute a massive rim the outside surface ofwhich advantageously is roughened or corrugated. This massive rimstrengthens the head of the drum decisively beside offering an idealpossibility for handling and with its high stiffness it counteractsespecially the feared distortion in the case when dropping down.Whenever the upper end closure is produced by way of the injectionmolding method, the bungs which have been also molded by the sameprocess are of a considerably higher precision and permit the use ofstandard bung plugs and sealing caps. Moreover they arein a protectedposition in the entry of the upper end closure which on its part iscompletely even and thus can also be written on and permits the use ofvacuum lift for loading.

Thus the invention makes use of the effect that blowmolded hollow bodiesmade of thermoplastics have after the blow-molding process aconsiderable linear delayed shrinkage, which moreover is fairly exactlydeterminable by partial control of the ejection temperature andvariation of the thickness of the wall and which can amount to up to 3%of the diameter in the case of a circular cross section. In. the case ofa drum opening of 500 mm diameter an engagement between the bordure ofthe drum and the upper bottom of 7.5 mm thus results at both sides, ameasurement which is fully sufficient for a safe connection of the twoparts. Since, in the case of the drum according to the invention, thereis an absolutely even thickness of the wall in the middle and the upperarea of the drum, the required consumption of material will thereby bereduced considerably. At the same time and as a result of the lowerweight of the body of the drum, as a result of the fact that the upperbottom is missing and as a result of the cooling which is more free oftension, the performance of the blow-molding machine increasesconsiderably, so that despite the additional manufacture of the upperbottom by way of the injection molding process, considerable technicaland economic advantages result in accordance with the method ofoperation of the invention.

What is claimed is: 1. A drum of the type having a plastic body portionand a separate plastic closure firmly seated within an end of the bodyportion, the improvement wherein:

said plastic body portion has an end which defines a groove-like borderincluding: an inwardly projecting circumferential bead-like bulge,

said bulge defining a generally radially inwardly projecting annulargripping recess;

an inwardly bent circumferential lip located outwardly of said bulgerelative to a longitudinal axis of the drum, and

an intermediate section extending between said bulge and said lip anddefining a generally radially outwardly projecting annular first groove;and

said plastic closure having circumferential margin means firmly anchoredwithin said groove-like border of said body portion to seal and resistdistortion of the latter while preventing removal of said closure fromsaid body portion, said margin means comprising:

a generally radially inwardly projecting annular second groove definedby axially spaced, generally radially outwardly extending flange parts,with said bulge being seated within said second groove, and said flangeparts each extending radially outwardly beyond the radial inner extentof said bulge such that said flange parts firmly engage opposite,longitudinally spaced surfaces of said bulge;

a generally radially inwardly projecting annular third groove locatedoutwardly of said second groove relative to a longitudinal axis of thedrum, said third groove being defined by axially spaced, generallyradially outwardly extending flange parts, with said lip being firmlyseated in said third groove; said last-named flange parts each extendingradially outwardly beyond the radial inner extent of said lip such thatsaid last-named flange parts firmly engage opposite, longitudinallyspaced surfaces of said lip;

said first groove of said body portion being configured to receive atleast one of said flange parts.

2. Apparatus according to claim 1 wherein the generally radial inwardextent of said bulge is greater than that of said edge; and thegenerally radial outward extent of said flange parts progressivelyincreases from the axially innermost flange to the axially outermostflange to facilitate installation of said cover into said drum.

3. A drum as defined in claim 1 wherein said flange parts comprise:

first and second axially spaced flange parts forming said second groove,and

third and fourth axially spaced flange parts forming said third groove;

said second and third flange parts being disposed axially between saidfirst and fourth flange parts and being received in said second grooveof said body portion;

said second flange part terminating short of said third flange part in agenerally radially outward extent to facilitate installation of saidclosure.

4. A drum as defined in claim 3 wherein a series of annularly spacedbridging brace elements are provided interconnecting said second andthird flange parts.

5. A drum as defined in claim 1 further including a gasket disposed inat least one of said second and third grooves in sealing relationshipbetween said cover and said body portion.

6. A drum as defined in claim 1 and further including corrugations on anoutside surface of said border of said body portion and on an insidesurface of said margin of said closure to facilitate handling of saiddrum.

7. A drum of the type having a plastic body portion and a separateplastic closure firmly seated within an end of the body portion, theimprovement wherein:

said plastic body portion has an end which defines a groove-like borderincluding: an inwardly projecting circumferential bead-like bulge, saidbulge defining a generally radially inwardly projecting annular grippingrecess; an inwardly bent circumferential lip located outwardly of saidbulge relative to a longitudinal axis of the drum, and an intermediatesection extending between said bulge and said lip and defining agenerally radially outwardly projecting annular first groove; and saidplastic closure having circumferential margin means firmly anchoredwithin said groove-like border of said body portion to seal and resistdistortion of the latter while preventing removal of said do sure fromsaid body portion, said margin means comprising: a generally radiallyinwardly projecting annular second groove defined by axially spaced,generally radially outwardly extending first and second flange parts,with said bulge being seated within said second groove, and a generallyradially inwardly projecting annular third groove located outwardly ofsaid second groove relative to a longitudinal axis of the drum, saidthird groove being defined by axially spaced, generally radiallyoutwardly extending third and fourth flange parts, with said lip beingfirmly seated in said third groove; said second and third flange partsbeing disposed axially inwardly between said first and fourth flangeparts and being received in said second groove of said body portion;

said second flange part terminating short of said third flange part in agenerally radially outward extent to facilitate installation of saidclosurev

1. A drum of the type having a plastic body portion and a separateplastic closure firmly seated within an end of the body portion, theimprovement wherein: said plastic body portion has an end which definesa groove-like border including: an inwardly projecting circumferentialbead-like bulge, said bulge defining a generally radially inwardlyprojecting annular gripping recess; an inwardly bent circumferential liplocated outwardly of said bulge relative to a longitudinal axis of thedrum, and an intermediate section extending between said bulge and saidlip and defining a generally radially outwardly projecting annular firstgroove; and said plastic closure having circumferential margin meansfirmly anchored within said groove-like border of said body portion toseal and resist distortion of the latter while preventing removal ofsaid closure from said body portion, said margin means comprising: agenerally radially inwardly projecting annular second groove defined byaxially spaced, generally radially outwardly extending flange parts,with said bulge being seated within said second groove, and said flangeparts each extending radially outwardly beyond the radial inner extentof said bulge such that said flange parts firmly engage opposite,longitudinally spaced surfaces of said bulge; a generally radiallyinwardly projecting annular third groove located outwardly of saidsecond groove relative to a longitudinal axis of the drum, said thirdgroove being defined by axially spaced, generally radially outwardlyextending flange parts, with said lip being firmly seated in said thirdgroove; said last-named flange parts each extending radially outwardlybeyond the radial inner extent of said lip such that said last-namedflange parts firmly engage opposite, longitudinally spaced surfaces ofsaid lip; said first groove of said body portion being configured toreceive at least one of said flange parts.
 2. Apparatus according toclaim 1 wherein the generally radial inward extent of said bulge isgreater than that of said edge; and the generally radial outward extentof said flange parts progressively increases from the axially innermostflange to the axially outermost flange to facilitate installation ofsaid cover into said drum.
 3. A drum as defined in claim 1 wherein saidflange parts comprise: first and second axially spaced flange partsforming said second groove, and third and fourth axially spaced flangeparts forming said third groove; said second and third flange partsbeing disposed axially between said first and fourth flange parts andbeing received in said second groove of said body portion; said secondflange part terminating short of said third flange part in a generallyradially outward extent to facilitate installation of said closure.
 4. Adrum as defined in claim 3 wherein a series of annularly spaced bridgingbrace elements are provided interconnecting said second and third flangeparts.
 5. A drum as defined in claim 1 further including a gasketdisposed in at least one of said second and third grooves in sealingrelationship between said cover and said body portion.
 6. A drum asdefined in claim 1 and further including corrugations on an outsidesurface of said border of said body portion and on an inside surface ofsaid margin of said closure to facilitate handling of said drum.
 7. Adrum of the type having a plastic body portion and a separate plasticclosure firmly seated within an end of the body portion, the improvementwherein: said plastic body portion has an end which defines agroove-like border including: an inwardly projecting circumferentialbead-like bulge, said bulge defining a generally radially inwardlyprojecting annular gripping recess; an inwardly bent circumferential liplocated outwardly of said bulge relative to a lonGitudinal axis of thedrum, and an intermediate section extending between said bulge and saidlip and defining a generally radially outwardly projecting annular firstgroove; and said plastic closure having circumferential margin meansfirmly anchored within said groove-like border of said body portion toseal and resist distortion of the latter while preventing removal ofsaid closure from said body portion, said margin means comprising: agenerally radially inwardly projecting annular second groove defined byaxially spaced, generally radially outwardly extending first and secondflange parts, with said bulge being seated within said second groove,and a generally radially inwardly projecting annular third groovelocated outwardly of said second groove relative to a longitudinal axisof the drum, said third groove being defined by axially spaced,generally radially outwardly extending third and fourth flange parts,with said lip being firmly seated in said third groove; said second andthird flange parts being disposed axially inwardly between said firstand fourth flange parts and being received in said second groove of saidbody portion; said second flange part terminating short of said thirdflange part in a generally radially outward extent to facilitateinstallation of said closure.